Biodegradable coated substrates

ABSTRACT

Coated substrates include a coating and a substrate is selected from the group consisting of paper, fabric, thread and yarn. The coating comprises a biodegradable polyhydroxyalkanoate copolymer, wherein the biodegradable polyhydroxyalkanoate copolymer comprises a first randomly repeating monomer unit having the structure:  
                 
 
     wherein  
     R 1  is H or a C 1-2  alkyl, and n is 1 or 2; and  
     a second randomly repeating monomer unit having the structure:  
                 
 
     wherein  
     R 2  is a C 3-19  alkyl or a C 3-19  alkenyl; and  
     wherein at least 50% of the randomly repeating monomer units have the structure of the first randomly repeating monomer unit.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of International ApplicationPCT/US01/18746, with an international filing date of Jun. 8, 2001, andpublished in English, which claims the benefit of U.S. ProvisionalApplication No. 60/210,618, filed Jun. 9, 2000.

TECHNICAL FIELD

[0002] This invention relates to substrates having a coating comprisingbiodegradable plastics. More particularly, this invention relates tosubstrates having a coating comprising biodegradablepolyhydroxyalkanoate copolymers.

BACKGROUND ART

[0003] Polymers find uses in a variety of plastic articles includingfilms, sheets, fibers, foams, molded articles, adhesives and many otherspecialty products. The majority of this plastic material ends up in thesolid waste stream. While some efforts at recycling have been made,repeated processing of even pure polymers results in degradation ofmaterial and consequently poor mechanical properties. Different gradesof chemically similar plastics mixed upon collection can causeprocessing problems that make the reclaimed material inferior orunusable. Thus, there is a need for plastics, including plasticcoatings, which are biodegradable.

[0004] Items such as juice boxes or foil food containers often areformed with laminates of plastics or foil. As such laminates oftencomprises non-biodegradable matters, these items must be removed fromthe stream of food waste and deposited in landfills. Thus, there is aneed for coatings which are biodegradable and yet resistance to greaseand water. Additionally, glossy finishes are often desired on paperproducts, such as printing or wrapping paper. Thus, there is a need forcoatings which are biodegradable and yet provide a glossy finish topaper.

[0005] Jaschek et al., U.S. Pat. No. 4,405,341, disclose a coated fabricconsisting of continuous multi-filament threads chemically activated androughened to improve adhesion coated with two layers of coatingscomprise a mix of a dispersable elastic and/or thermoplastic substancewith a highly cross-linked duroplastic substance.

[0006] Smith, U.S. Pat. No. 4,632,874, discloses a substantiallyhomogenous aqueous composition for imparting coherency to textilefilaments and textile yarns, comprising an emulsifiable textilefinishing oil and a water dissipatable polymer. Smith teaches thatfilaments of any yarn must to some degree have coherency to prevent thefilaments or fibers from becoming tangle masses.

[0007] Dahmen et al., U.S. Pat. No. 4,774,131, disclose a process forthe production of a textile surface coated with polyurethane, comprisingwet coating the textile materials with an aqueous cationic dispersion ofa polyurethane with covalently bonded, solubility-enhancing, cationicgroups and an aqueous, anionic dispersion of a polyurethane withcovalently bonded, solubility-enhancing, anionic groups. Dahmen et al.teach that textiles are useful for the production of breathable andwater-proof clothing, and subsequently drying the coated material, theimprovement which comprises applying to the textile surface.

[0008] Van Gompel, U.S. Pat. No. 4,797,171, discloses a method of makinga coated fabric comprising providing a base ply of non-woven fibermaterial; forming in the base ply material a pattern of densified andundensified portions, the densified portions extending to at least onesurface, designated the coating surface; then providing a thermoplasticfilm in a heat-softened condition; contacting the heat-softenedthermoplastic film with the coating surface of the base ply; controllingthe depth of penetration of the heat-softened thermoplastic film to adepth less than the entire depth of the base ply by maintaining thetemperature of the film and the contact pressure between the film andthe base ply at predetermined values, and allowing the surface coatingof film to cool.

[0009] Malhotra, U.S. Pat. No. 5,075,153, discloses a coated papercomprising a plastic supporting substrate, a binder layer composed ofpolymer selected from the group consisting of hydroxypropylcellulose,poly(vinyl alkylether), vinyl pyrrolidone/vinyl acetate, quaternizedvinyl pyrrolidone/dialkylaminoethyl/methylacrylic,pyrrolidone/dialkylaminoethyl/methylacrylic, poly(vinyl pyrrolidone),poly(ethylene imine), and mixtures thereof, a pigment or pigments, andan ink receiving polymer layer. Malhotra teaches the supportingsubstrate may be a polyester.

[0010] Doran, U.S. Pat. No. 5,194,322, discloses a coated textilematerial comprising a textile substrate having a microporous coating ofan elastomeric copolymer wherein at least one component thereof is afluorocarbon, wherein the coating is formed as a compressed foam layerat the surface of the textile substrate, the layer being compressed onthe surface and set to form a coherent coarse membrane.

[0011] Pommeranz et al., U.S. Pat. No. 5,306,544, disclose a paper webfor producing trays or coasters comprising a hygroscopic support paperand a sliding reducing means on one side wherein the sliding reducingmeans includes a coating forming a discrete structure on the supportpaper and consisting of butylacrylate and methylacrylamide.

[0012] Di Mino, U.S. Pat. No. 5,470,594, discloses a recyclable pouchfor packaging food products comprising two superposed plies, each formedby at least one sheet of paper, each ply having an interface coated witha layer of water-based acrylic polymer having a low glass transitiontemperature and an outer face coated with a water-based acrylic polymerhaving a relatively high glass transition temperature, the superposedplies being sealed together in a pre-determined sealing pattern by heatand pressure which brings about fusion of the inner layer. Di Minoteaches each ply may be composed of two sheets of paper which arelaminated with a water-based acrylic adhesive. Di Mino further teachesthat the nature of the adhesive and the acrylic layers is such that thepaper pouch lends itself to being recycled.

[0013] Quick et al., U.S. Pat. No. 5,763,100, teach a recyclable paperstock comprising a substrate coated on at least one surface with awater-based emulsion coating, the coating consisting essentially of 20to 90 dry weight percent of an acrylic-styrene copolymer which consistsessentially of acrylic monomers and styrene having a glass transitiontemperature below 50° C.; 5 to 70 dry weight percent of a wax componentselected from the group consisting of paraffin wax, microcrystallinewax, polyethylene wax, and blends of two or more of the waxes; and anacrylic polymer having a glass transition temperature above 30° C.present in amount up to 60 dry weight percent, wherein the coating formsa water-resistant film on the substrate surface.

[0014] Finestone et al., U.S. Pat. No. 5,786,064, disclose a paper-filmlaminate sheeting comprising a paper ply having top and bottom surfaces,a reinforcing ply of a synthetic plastic film material having top andbottom surfaces, a water-based adhesive layer for laminating the bottomsurface of the paper ply to the top surface of the reinforcing ply, andfiberglass strands between the paper and reinforcing plies to increasethe strength of the sheeting, wherein the top surface of the film isactivated by corona discharge treatment prior to contact by theadhesive, and the sheeting includes a plurality of minute pores whichare uniformly distributed throughout. Finestone et al. teach thelaminate sheeting is permeable only to moisture vapor, and can betailored to form water-proof yet breathable garments.

[0015] Nielsen et al., U.S. Pat. No. 5,795,320 disclose an applicatorcomprising a tubular member formed from a single layer of paper havingan exterior surface, and a coating applied to the exterior surface, thecoating being a single layer of compostable material and comprising atleast 85% by weight of a polylactide polymeric material, at least 10% byweight of additives, and up to 5% by weight of a residual monomer,wherein the coating provides the tubular member with a dry coefficientof kinetic friction value ranging from between 0.62 to 0.86. Nielsen etal. teach the paper applicator which has a compostable coating on itsexternal surface closely approximates the esthetic appearance of aplastic applicator and has a lower coefficient of friction than aplastic applicator.

[0016] El-Afandi et al., U.S. Pat. No. 5,849,401, disclose a compostablemulti-layer film comprising a core layer comprising a lactic acidresidue-containing polymer, and a first and second blocking reducinglayers comprising a semi-crystalline aliphatic polyester. El-Afandi etal. teach that the compostable multi-layer structures are films havingdesirable properties of flexibility and tear resistance and can be usedto provide disposable bags.

[0017] Bloch et al., U.S. Pat. No. 5,962,099, disclose a pressuresensitive sealing tape consisting essentially of a thin biaxiallyoriented synthetic-plastic film ply formed of a material selected fromthe group consisting of polypropylene, polyethylene and polyester, apaper ply cold laminated by water-based adhesive to the film ply, and alayer of pressure sensitive adhesive coating one side of the laminate,and a release agent coating the other side of the laminate to preventblocking.

[0018] Unfortunately, many prior art plastic items compriseplasticizers. Additionally, many prior service items paper or plasticbags are lacking in strength or have poor water permeation resistanceand/or grease permeation resistance. Further, many biodegradable plasticitems are brittle, or are incapable of degrading under both aerobic andanaerobic conditions.

[0019] Additionally, prior art polymers such as polyhydroxybutyrate andpolyhydroxybutyrate-co-valerate often have unsatisfactory properties.Polyhydroxybutyrate and polyhydroxybutyrate-co-hydroxyvalerate tends tobecome thermally unstable near their melt temperatures which makeprocessing difficult. It is preferred that the melting temperature of abiodegradable material be substantically lower that its decompositiontemperature, or the temperature at which molecular weight substantiallydecreases due to hydrolysis.

[0020] There is a need for polymers which are strong without beingbrittle, which are easy to process and which will biodegrade under bothaerobic and anaerobic conditions. Further, there is a need for coatingswhich improve the water and grease resistance of paper and fabric, andwill can impart a gloss to paper.

SUMMARY OF THE INVENTION

[0021] Accordingly, it is an object of this invention to obviate variousproblems of the prior art.

[0022] It is also object of this invention to provide coated substrateswhich can be anaerobically degraded without harm to the ecosystem.

[0023] It is another object of this invention to provide coated paperand coated fabric which have good water and grease resistancecharacteristics. As used herein, “liquid resistance” and “greaseresistance” refer to the ability of an item to resist penetration orleakage by liquid and grease, respectively.

[0024] It is yet another object of this invention to providebiodegradable coated substrates which are substantially free ofphthalate plasticizers.

[0025] It is another object of this invention to provide biodegradablecoated substrates from biodegradable polymers which are easilyprocessed.

[0026] It is yet another object of this invention to providebiodegradable coated paper which has a glossy surface.

[0027] In accordance with one aspect of the invention there are providedcoated substrates comprising a substrate and a coating. The coatingcomprises a biodegradable polyhydroxyalkanoate copolymer, comprising afirst randomly repeating monomer unit having the structure:

[0028] wherein

[0029] R¹ is H or a C₁₋₂ alkyl, and n is 1 or 2; and

[0030] a second randomly repeating monomer unit having the structure:

[0031] wherein

[0032] R² is a C₃₋₁₉ alkyl or a C₃₋₁₉ alkenyl; and

[0033] wherein at least 50% of the randomly repeating monomer units havethe structure of the first randomly repeating monomer unit. Thesubstrate is selected from the group consisting of paper, fabric, threadand yarn.

[0034] In accordance with another aspect of the invention there areprovide methods of, improving the resistance to grease of a substrate,comprising the step of applying a coating to a substrate selected fromthe group consisting of paper, fabric, thread and yarn. The coatingcomprises a biodegradable polyhydroxyalkanoate copolymer comprising tworandomly repeating monomer units wherein the first randomly repeatingmonomer unit has the structure:

[0035] wherein

[0036] R¹ is H or a C₁₋₂ alkyl, and n is 1 or 2; and,

[0037] the second randomly repeating monomer unit has the structure:

[0038] wherein

[0039] R² is a C₃₋₁₉ alkyl or a C₃₋₁₉ alkenyl; and

[0040] wherein at least 50% of the randomly repeating monomer units havethe structure of the first randomly repeating monomer unit.

[0041] In accordance with yet another aspect of the invention there areprovide methods of improving the resistance to water of a substrate,comprising the step of applying a coating to a substrate selected fromthe group consisting of paper and fabric. The coating comprises abiodegradable polyhydroxyalkanoate copolymer comprising two randomlyrepeating monomer units wherein the first randomly repeating monomerunit has the structure:

[0042] wherein

[0043] R¹ is H or a C₁₋₂ alkyl, and n is 1 or 2; and

[0044] the second randomly repeating monomer unit has the structure:

[0045] wherein

[0046] R² is a C₃₋₁₉ alkyl or a C₃₋₁₉ alkenyl; and

[0047] wherein at least 50% of the randomly repeating monomer units havethe structure of the first randomly repeating monomer unit.

[0048] In accordance with yet another aspect of the invention there areprovide methods of providing a gloss on paper, comprising the step ofapplying a coating to the paper, wherein the coating comprises abiodegradable polyhydroxyalkanoate copolymer, comprising two randomlyrepeating monomer units wherein the first randomly repeating monomerunit has the structure:

[0049] wherein

[0050] R¹ is H or a C₁₋₂ alkyl, and n is 1 or 2; and

[0051] the second randomly repeating monomer unit has the structure:

[0052] wherein

[0053] R² is a C₃₋₁₉ alkyl or a C₃₋₁₉ alkenyl; and

[0054] wherein at least 50% of the randomly repeating monomer units havethe structure of the first randomly repeating monomer unit. The coatingimproves the resistance to water of the item and is capable of aerobicand anaerobic degradation.

DETAILED DESCRIPTION OF THE INVENTION

[0055] As used herein, “PHA” refers to a polyhydroxyalkanoate polymer ofthe present invention. Applicants have found that compositionscomprising polyhydroxyalkanoate polymers (PHAs) provide useful coatingsfor substrates such as paper, fabric, thread and yarn. PHAs inaccordance with the present invention will biodegrade under both aerobicand anaerobic conditions, thus, items formed from the PHAs canbiodegrade even when under water. The PHAs may be disposed of into thefood waste stream as a mixture of food waste and PHAs, for example, foodwaste and paper substrates having a coating comprising PHA may becomposted together. Biodegradation of the PHAs will occur without harmto the environment, microorganisms or animals.

[0056] Biodegradable items in accordance with the invention areunexpectantly resistant to liquids and grease. The items are formed fromPHAs exhibit surprisingly good heat-sealability and adhesion to papersubstrates.

[0057] Further, unlike the homopolymer poly(3-hydroxybutyrate) (PHB) orthe copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), PHAsin accordance with the invention are tough without being brittle. Thusitems comprising the PHAs are less likely to crack or delaminate.Applicants have found that polyhydroxyalkanoates in accordance with thepresent invention have lower melt temperatures, lower degrees ofcrystalinity and improved melt rheologies relative topolyhydroxybutyrate and poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Asthe PHAs of the present invention have low melting temperatures, thePHAs can be processed into films and coatings. The PHAs of the presentinvention have melting temperatures lower than their decompositiontemperatures, or the temperature at which substantial MW loss due tohydrolysis occurs.

[0058] As used herein, the term “coating” is intended to refer to both alayer exclusively on the surface of a substrate as well as a layer whichto some degree penetrates the substrate. Suitable substrates includepaper, fabric, thread and yarn. Often the substrate will be paper. Asused herein, “paper” refers to a substrate formed from cellulose fiber,including paper and cardboard. As used herein, “fabric” includes naturaland synthetic fabrics. The fabrics may be knitted, woven or non-woven.Suitable fabrics include cotton, rayon, wool, and polyesters, as well asbiodegradable fabrics comprising PHAs. As used herein, “thread and yarn”includes natural and synthetic threads and yarns, such as cotton, rayon,polyester, wool, silk, nylon, and acrylic as well as biodegradablethreads and yarns comprising PHAs. Thread and yarn may be formed usingfibers of PHA. As used herein, “fiber” refers to a flexible,macroscopically homogeneous body having a high length-to-width ratio anda small cross section.

[0059] A coating comprising PHA improves the water and grease resistancesubstrates, and provides the substrate with a smoother surface. Thecoating may be applied to one or two sides of a substrate such as paperor fabric.

[0060] Coated paper may be used as backing for tape; preferably the tapecomprises paper, a coating comprising PHA and an adhesive, preferably anadhesive comprising PHA.

[0061] Fabric and paper coated with PHA can be used to form items withimproved water and grease resistance, such as wrapping paper, paperbags, plastic bags, cardboard containers, drink boxes, trays, tableclothes, napkins, rain coats and ponchos, and disposable garments suchas surgical scrubs. Thread and yarn coated with PHA have a smoothersurface than untreated thread or yarn, and are less likely to tangle.Disposable garment seams may be sewn with thread, preferably aPHA-coated thread, or may be joined with an adhesive, preferably abiodegradable adhesive comprising a PHA.

[0062] As used herein, “RRMU” refers to a randomly repeating monomerunit and “RRMUs” refers to randomly repeating monomer units. As usedherein, “alkyl” refers to a saturated carbon-containing chain which maybe straight or branched, and substituted (mono- or poly-) orunsubstituted, while, “alkenyl” refers to a carbon-containing chainwhich may be mono-unsaturated (i.e., one double bond in the chain) orpoly-unsaturated (i.e., two or mor double bonds in the chain), straightor branched, and substituted (mono- or poly-) or unsubstituted.

[0063] As used herein, “biodegradable” refers to the ability of acompound to ultimately be degraded completely into CH₄, CO₂ and water orbiomass by microorganisms and/or natural environmental factors.

[0064] As used herein, “compostable” refers to a material that meets thefollowing three requirements: (1) the material is capable of beingprocessed in a composting facility for solid waste; (2) if so processed,the material will end up in the final compost; and (3) if the compost isused in the soil, the material will ultimately biodegrade in the soil.

[0065] For example, a polymer film material present in solid wastesubmitted to a composting facility for processing does not necessarilyend up in the final compost. Certain composting facilities subject thesolid waste stream to air classification prior to further processing, inorder to separate paper and other materials. A polymer film would mostprobably be separated from the solid waste stream in such an airclassification and therefore not be processed in the compostingfacility. Nevertheless, it may still be a “compostable” materialaccording to the above definition because it is “capable” of beingprocessed in a composting facility.

[0066] The requirement that the material ends up in the final composttypically means that it undergoes a form of degradation in thecomposting process. Typically, the solid waste stream will be subjectedto a shredding step in an early phase of the composting process. As aresult, the polymer film will be present as shreds rather than a sheet.In the final phase of the composting process, the finished compost willbe subjected to a screening step. Typically, the polymer shreds will notpass through the screens if they have retained the size they hadimmediately after the shredding step. The compostable materials of thepresent invention will have lost enough of their integrity during thecomposting process to allow partially degraded shreds to pass throughthe screens. However, it is conceivable that a composting facility mightsubject the solid waste stream to a very rigorous shredding and a rathercoarse screening, in which case nondegradable polymers like polyethylenewould meet requirement (2). Therefore, meeting requirement (2) is notenough for a material to be compostable within the present definition.

[0067] What distinguishes the compostable material as defined hereinfrom material like polyethylene is requirement (3), that the materialultimately biodegrade in the soil. This biodegradability requirement isnot essential to the composting process or the use of composting soil.Solid waste and the compost resulting therefrom may contain all kinds ofnonbiodegradable materials, for example, sand. However, to avoid a buildup of man-made materials in the soil, it is required herein that suchmaterials be fully biodegradable. By the same token, it is not at allnecessary that this biodegradation be fast. As long as the materialitself and intermediate decomposition products are not toxic orotherwise harmful to the soil or crops, it is fully acceptable thattheir biodegradation takes several months or even years, since thisrequirement is present only to avoid an accumulation of man-madematerial in the soil.

[0068] All copolymer composition ratios recited herein refer to molarratios, unless specifically indicated otherwise. All percentages andparts are by weight, unless specifically indicated otherwise.

[0069] The polyhydroxyalkanoates used in the present invention made besynthetically prepared, or may be produced by a variety of biologicalorganisms, such as bacteria or algae. The polyhydroxyalkanoates may beatactic, isotactic or syndiotactic. The polyhydroxyalkanoates usedherein are preferably substantially isotactic (from about 90% to about100%, by weight, isotactic) or fully isotactic (about 100%, by weight,isotactic). The fully isotactic polyhydroxyalkanoates may be obtainedfrom biological organisms, preferably polyhydroxyalkanoates used hereinare obtained from biological organisms.

[0070] The polyhydroxyalkanoates are copolymers comprising at leastabout 2 different monomers. In some embodiment, thepolyhydroxyalkanoates are copolymers comprising at least about 3different monomers.

[0071] In one embodiment, the polyhydroxyalkanoate comprises at leasttwo randomly repeating monomer units (RRMUs). The first randomlyrepeating monomer unit has the structure:

[0072] wherein

[0073] R¹ is H or a C₁₋₂ alkyl, and n is 1 or 2. In a preferredembodiment, the first randomly repeating monomer unit is selected fromthe group consisting of the monomer wherein R¹ is a C₁ alkyl and n is 1(the monomeric repeat unit 3-hydroxybutyrate); the monomer wherein R¹ isa C₂ alkyl and n is 1 (the monomeric repeat unit 3-hydroxyvalerate); themonomer wherein R¹ is H and n is 2 (the monomeric repeat unit4-hydroxybutyrate); the monomer wherein R¹ is H and n is 1 (themonomeric repeat unit 3-hydroxypropionate); and mixtures thereof.

[0074] The second randomly repeating monomer unit has the structure:

[0075] wherein

[0076] R² is a C₃₋₁₉ alkyl or a C₃₋₁₉ alkenyl. Suitable second RRMUsinclude those wherein R² is a C₃₋₇ alkyl or alkenyl, a C₅ alkyl oralkenyl, a C₇ alkyl or alkenyl, a C₈₋₁₁ alkyl or alkenyl, a C₈ alkyl oralkenyl, a C₉ alkyl or alkenyl, a C₁₂₋₁₉ alkyl or alkenyl, a C₃₋₁₁ alkylor alkenyl, or a C₄₋₁₉ alkyl or alkenyl.

[0077] Suitable polyhydroxyalkanoates includepoly(3-hydroxybutyrate-co-3-hydroxyhexanoate)s (PHB-Hxs) andpoly(3-hydroxybutyrate-co-3-hydroxyoctanoate)s (PHB—Os). In oneembodiment, the coating comprises a polyhydroxyalkanoates selected fromthe group consisting of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)12.1% hexanoate (PHB-Hx 12.1%), poly(hydroxybutrate-co-hydroxyhexanoate)11.1 mol % hexanoate (PHB-Hx 11%),poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) 8.4% octanoate (PHB—O8.4%), poly(3-hydroxy butyrate-co-3-hydroxyoctanoate) 13% octanoate(PHB—O 13%).

[0078] In one embodiment of the present invention, at least about 50%,preferably at least about 60%, more preferably at least about 70%, evenmore preferably at least about 80%, more preferably still at least about85%, of the RRMUs have the structure of the first RRMU.

[0079] When one or more of the polyhydroxyalkanoates of the presentinvention are processed into films or sheets preferably from about 70%to about 99%, more preferably from about 80% to about 95%, even morepreferably from about 85% to about 92%, of the RRMUs of the PHA have thestructure of the first RRMU.

[0080] In one embodiment the films or sheets are solution cast films orsheets. Generally from about 70% to about 99%, preferably from about 80%to about 95%, more preferably from about 85% to about 92%, of the RRMUsof the PHAs used to prepare solution cast films or sheets have thestructure of the first RRMU.

[0081] In one embodiment the films or sheets are melt pressed films orsheets. Generally from about 70% to about 99%, preferably from about 80%to about 95%, more preferably from about 85% to about 92%, of the RRMUsof the PHAs used to prepare melt pressed films or sheets have thestructure of the first RRMU.

[0082] When one or more of the polyhydroxyalkanoates of the presentinvention are processed into coating compositions, generally from about75% to about 95%, preferably from about 80% to about 92%, morepreferably from about 85% to about 90%, of the RRMUs of the PHAs havethe structure of the first RRMU.

[0083] In one embodiment, the coating composition is in the form of asolution comprising PHA. The solution further comprises a solvent inwhich the PHA is soluble, such as CHCl₃, ethylactelate, acetone, tolueneand mixture thereof. Generally from about 75% to about 95%, preferablyfrom about 80% to about 92%, more preferably from about 85% to about90%, of the RRMUs of the PHAs used to form the solution have thestructure of the first RRMU.

[0084] In one embodiment, the coating composition is in the form of adispersion comprising PHA. The solution further comprises a solvent inwhich the PHA forms a suspension, such as hexane, ethanol, methanol,mineral oil and water. Generally from about 75% to about 95%, preferablyfrom about 80% to about 92%, more preferably from about 85% to about90%, of the RRMUs of the PHAs used to form the suspension have thestructure of the first RRMU.

[0085] In one embodiment, the coating composition is in the form of anaqueous slurry comprising PHA. Generally from about 80% to about 95%,preferably from about 82% to about 92%, more preferably from about 85%to about 90%, of the RRMUs of the PHAs used to form the slurry have thestructure of the first RRMU.

[0086] When the polyhydroxyalkanoates of the present invention areprocessed soft elastic fibers, preferably from about 50% to about 98%,more preferably from about 80% to about 97%, even more preferably fromabout 85% to about 96%, of the RRMUs of the PHAs have the structure ofthe first RRMU.

[0087] When the polyhydroxyalkanoates of the present invention areprocessed into normal fibers, preferably from about 80% to about 99%,more preferably from about 90% to about 98%, even more preferably fromabout 95% to about 97%, of the RRMUs of the PHAs have the structure ofthe first RRMU.

[0088] When the polyhydroxyalkanoates of the present invention areprocessed into elastomers or an adhesives, such as bandage adhesives,preferably about 50% more preferably at least 65% of the RRMUs of thePHAs have the structure of the first RRMU.

[0089] When the polyhydroxyalkanoates of the present invention areprocessed into nonwoven fabrics, preferably from about 85% to about 99%,more preferably from about 90% to about 98%, even more preferably fromabout 95% to about 97%, of the RRMUs of the PHAs have the structure ofthe first RRMU.

[0090] In a preferred embodiment, the first randomly repeating monomerunit is selected from the group consisting of the monomer wherein R¹ isa C₁ alkyl and n is 1 (the monomeric repeat unit 3-hydroxybutyrate); themonomer wherein R¹ is a C₂ alkyl and n is 1 (the monomeric repeat unit3-hydroxyvalerate); the monomer wherein R¹ is H and n is 2 (themonomeric repeat unit 4-hydroxybutyrate); the monomer wherein R¹ is Hand n is 1 (the monomeric repeat unit 3-hydroxypropionate); and mixturesthereof.

[0091] In another embodiment, the polyhydroxyalkanoate of the presentinvention comprises a third or more additional RRMUs having thestructure:

[0092] wherein

[0093] R³ is H, a C₁₋₁₉ alkyl or a C₁₋₁₉ alkenyl, and m is 1 or 2; andwherein the additional RRMUs are not the same as the first RRMU or thesecond RRMU. In one embodiment the copolymer comprises from at leastabout 3, more preferably from about 3 to about 20 different RRMUs.

[0094] In one embodiment, R³ is a C₁₋₁₉ alkyl or a C₁₋₁₉ alkenyl, and mis 1, while in another embodiment R³ is a H, a C₁₋₂ alkyl or a C₁₋₂alkenyl, and m is 1 or 2. In a preferred embodiment, the third RRMU isselected from the group consisting of the monomer wherein R³ is a C₁alkyl and m is 1 (the monomeric repeat unit 3-hydroxybutyrate); themonomer wherein R³ is a C₂ alkyl and m is 1 (the monomeric repeat unit3-hydroxyvalerate); the monomer wherein R³ is H and m is 2, (themonomeric repeat unit 4-hydroxybutyrate); the monomer wherein R³ is Hand m is 1, (the monomeric repeat unit 3-hydroxypropionate) and mixturesthereof.

[0095] In another embodiment a polyhydroxyalkanoate according to thepresent invention comprises two RRMUs wherein the first RRMU has thestructure:

[0096] wherein

[0097] R¹ is H or a C₂ alkyl, and n is 1 or 2; and the second RRMU hasthe structure:

[0098] Preferably at least about 50% of the RRMUs have the structure ofthe first RRMU.

[0099] The one embodiment a polyhydroxyalkanoate according to thepresent invention comprises three RRMUs, a first RRMU having thestructure:

[0100] wherein

[0101] R¹ is H or a C₁₋₂ alkyl, and n is 1 or 2; a second RRMU havingthe structure:

[0102] wherein

[0103] R² is a C₃₋₁₉ alkyl or a C₃₋₁₉ alkenyl, preferably a C₄₋₁₉ alkylor a C₄₋₁₉ alkenyl; and a third RRMU having the structure:

[0104] wherein

[0105] R³ is H, a C₁₋₁₉ alkyl or a C₁₋₁₉ alkenyl, and m is 1 or 2; andwherein the third RRMU is not the same as the first RRMU or the secondRRMU. Preferably at least 50% of the RRMUs have the structure of thefirst RRMU.

[0106] Preferably, the molecular weight of the polyhydroxyalkanoates isgreater than about 25,000. In one embodiment the weight averagemolecular weight is no greater than about 400,000. In another embodimentthe weight average molecular weight is greater than about 400,000,preferably greater than 500,000.

[0107] The volume percent crystalinity (Φ_(c)) of a semi-crystallinepolymer (or copolymer) often determines what type of end-use propertiesthe polymer possesses. For example, highly (greater than 50%)crystalline polyethylene polymers are strong and stiff, and suitable forproducts such as plastic cups. Low crystalline polyethylene, on theother hand, is flexible and tough, and is suitable for products such asbags. Crystalinity can be determined in a number of ways, includingx-ray diffraction, differential scanning calorimetry (DSC), densitymeasurements, and infrared absorption, as discussed by Noda, U.S. Pat.No. 5,618,855, incorporated herein by reference.

[0108] In general, PHAs of the present invention preferably have acrystalinity of from about 0.5% to about 95% as measured via x-raydiffraction; more preferably from about 10% to about 80%; morepreferably still from about 20% to about 60%.

[0109] When a PHA of the present invention is to be processed into afilm, the amount of crystalinity in such PHA is more preferably fromabout 2% to about 65% as measured via x-ray diffraction; more preferablyfrom about 5% to about 50%; more preferably still from about 20% toabout 40%.

[0110] When a PHA of the present invention is to be processed into asheet, the amount of crystalinity in such PHA is more preferably fromabout 0.1% to about 50% as measured via x-ray diffraction; morepreferably from about 5% to about 50%; more preferably still from about20% to about 40%.

[0111] When a PHA of the present invention is to be processed into acoating composition in the form of a solution, the amount ofcrystalinity in such PHA is more preferably from about 15% to about 60%as measured via x-ray diffraction; more preferably from about 20% toabout 50%; more preferably still from about 30% to about 40%.

[0112] When a PHA of the present invention is to be processed into acoating composition in the form of a suspension, the amount ofcrystalinity in such PHA is more preferably from about 15% to about 60%as measured via x-ray diffraction; more preferably from about 20% toabout 50%; more preferably still from about 30% to about 40%.

[0113] When a PHA of the present invention is to be processed into acoating composition in the form of a slurry, the amount of crystalinityin such PHA is more preferably from about 15% to about 60% as measuredvia x-ray diffraction; more preferably from about 20% to about 50%; morepreferably still from about 30% to about 40%.

[0114] When a PHA of the present invention is to be processed into anormal fiber or a nonwoven fabric, the amount of crystalinity in suchPHA is more preferably from about 50% to about 95% as measured via x-raydiffraction; more preferably from about 60% to about 95%; morepreferably still from about 70% to about 95%.

[0115] When a PHA of the present invention is to be processed into asoft elastic fiber, the amount of crystalinity in such PHA is morepreferably from about 20% to about 90% as measured via x-raydiffraction; more preferably from about 30% to about 85%; morepreferably still from about 40% to about 80%.

[0116] When a PHA of the present invention is to be processed into anelastomer or adhesive, the amount of crystalinity in such PHA is morepreferably less than about 50% as measured via x-ray diffraction; morepreferably less than about 30%; more preferably still less than about20%.

[0117] Preferably, the biodegradable PHAs of the present invention havea melt temperature (Tm) of from about 30° C. to about 160° C., morepreferably from about 60° C. to about 140° C., more preferably stillfrom about 90° C. to about 130° C.

[0118] Suitable polyhydroxyalkanoates include those disclosed in Noda,U.S. Pat. Nos. 5,498,692; 5,502,116; 5,536,564; 5,602,227; 5,618,855;5,685,756; and 5,747,584, incorporated herein by reference.

[0119] The coatings may serve as barriers, decorative coatings, or forother purposes. Coating may be used to apply adhesive for laminating oneweb to another or for manufacturing of pressure-sensitive tapes andlabels. It also may be used for saturation of a porous web substrate,such as paper, in order to improve its resistance to moisture or greasepenetration, or to improve its strength.

[0120] The thickness of a coating is generally measured in “mils”. Onemil is equal to 0.001 inch. The substrates generally have a coating upto 5, preferably from about 4 to about 0.5, more preferably from about 2to about 1, mils thick. Paper substrates generally have a coating with athickness of from about 5 to about 0.5, preferably from about 2 to e.g.,about 1, mils, while fabric substrates generally have a coating with athickness of from about 5 to about 1, preferably from about 3 to about2, mils. Thread and yarn substrates generally have a thinner coatingthan paper or fabric substrates, such as a thickness of from about 2 toabout 0.2, preferably from about 1 to about 0.5, mils.

[0121] The coatings may comprise additives such as colorants.Preferably, such colorants are nonfugitive. As used herein,“nonfugitive” refers to an additive that does not escape from thepolyhydroxyalkanoate copolymer at a faster rate than which the copolymerbiodegrades. The coatings herein may be formed from a compositioncomprising the biodegradable polyalkanoate copolymer and colorant.Alternatively, colors and designs may be printed on the items aftermanufacture. Preferably the colorants are non-toxic. Some items, such asgarbage bags, may have coatings comprising deodorants, fragrances ordisinfectants.

[0122] Many plastic items comprise plasticizers such as phthalateplasticizers or adipic acid derivatives such as di-2 ethyl hexyladipate. Phthalate plasticizers refer to compounds comprising aphthalate group used as plasticizers. Such plasticizers includebis-2-ethylhexyl phthalate, also referred to as dioctyl phthalate (DOP)and di-2-ethylhexyl phthalate (DEHP), and diusononyl phthalate (DINP).Other phthalate plasticizers include butyl benzyl phthalate, butyl octylphthalate, di-n-butyl phthalate, dicapryl phthalate, dicyclohexylphthalate, diethyl phthalate, dihexyl phthalate, diisobutyl phthalate,diisodecyl phthalate, diisohectyl phthalate, diisooctyl phthalate,dimethyl phthalate, ditridecyl phthalate, diundecyl phthalate, undecyldodecyl phthalate and mixtures thereof.

[0123] However, there is concern that plasticizers, particularlyphthalate plasticizers may leach from plastic items. Thus, in oneembodiment the coatings and coated substrates are preferablysubstantially free of, more preferably free of, plasticizers,particularly phthalate plasticizers. As used herein, substantially freeof means preferably no greater than 20%, more preferably no greater than10%, even more preferably less than 5%, by weight, of the item isplasticizers.

[0124] In another embodiment, the coatings and coated substrates maycontain plasticizers, preferably non-toxic and biodegradableplasticizers. Suitable plasticizers include tricarboxylic esters,citrate esters, esters of glycerine and dicarboxylic esters. A preferredplasticizer is triacetin, also called glyceryl triactetate or1,2,3-propanetriol triacetate. Generally, coatings containingplasticizers comprises from about 40% to about 3%, preferably from about20% to about 5%, by weight of total coating, plasticizer, and from about59% to about 96%, preferably from about 79% to about 94%, by weight oftotal coating, PHA. In one embodiment the coating comprises apolyhydroxyalkanoate in accordance with the invention, triacetin, andpolyhydroxybutyrate (PHB), in a weight ratio of from about 50% to 95%PHA, 45% to 4% triaretin, 5% to 1% PHB, more preferred 70-92% PHA, 26 to7% plasticizer, 4% to 1% PHB. Most preferred about 85:13:2PHA:plastizer:PHB. Suitable polyhydroxyalkanoates includepoly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHB-Hx) andpoly(3-hydroxybutyrate-co-3-hydroxyoctanoate) (PHB—O).

[0125] In one embodiment of the invention, coated substrates comprise acoating comprising a biodegradable polyhydroxyalkanoate comprising atleast two randomly repeating monomer units. In one embodiment the PHAcomprises a first randomly repeating monomer unit having the structure:

[0126] wherein

[0127] R¹ is H or a C₁₋₂ alkyl, and n is 1 or 2; and a second randomlyrepeating monomer unit having the structure:

[0128] wherein

[0129] R² is a C₃₋₁₉ alkyl or a C₃₋₁₉ alkenyl, preferably a C₄₋₁₉ alkylor a C₄₋₁₉ alkenyl.

[0130] In another embodiment the polyhydroxyalkanoate comprises a thirdrandomly repeating monomer unit having the structure:

[0131] wherein

[0132] R³ is H, a C₁₋₁₉ alkyl or a C₁₋₁₉ alkenyl, and m is 1 or 2, andthe third RRMU is not the same as the first RRMU or the second RRMU.Polyhydroxyalkanoate copolymers comprising three RRMUs will generallycomprise, by weight, at least about 50% of the first RRMU, and generallyno greater than about 20% of the third RRMU. The composition maycomprise at least about 4%, more preferably at least about 5%, and evenmore preferably at least about 8%, and no more than about 15%,preferably no more than about 12%, more preferably no more than about10%, by weight, of the third RRMU. The preferred levels of monomers isdependent upon the desired characteristic of the article, for example,when using a rigid substrate, such as paper, a thicker or stiffercoating may be desired than when using a flexible substrate, such asfabric.

[0133] The PHAs used as coatings preferably comprise a first RRMU havingformula (i) above, and a second RRMU having formula (ii) above.Preferably the weight average of molecular weight of the copolymer isgreater than 50,000, preferably greater than about 100,000. In oneembodiment the PHAs used as coatings comprise from about 4% to about20%, preferably at least about 5%, by weight of total PHA, of the thirdRRMU having the formula (iii) above.

[0134] Coated articles may be formed using any conventional coatingtechniques or coating equipment. Coating techniques include extrusioncoating, roller coating, brush coating, dip coating, spray coating,electrostatic coating, centrifugal coating and cast coating. Articlesmay be coated with melted PHA, and then exposed to a coolant, such aswater, by any acceptable method, such as dipping or spraying. Substratesmay be laminated with a sheet or film comprising PHA, such as a solutioncast film or a melt pressed film. Slurries, suspensions or solutionscomprising PHA may be applied to a substrate, and the substrate thenallowed to dry and, optionally, pressed.

[0135] Coatings applied in a non-solid form must be sufficiently fluidto be spread into a uniformly thin layer across the substrate.Therefore, coatings are applied as solutions in organic solvents, asaqueous solutions or emulsions, as a hot melt (solid molten or softenedby heat), or as a reactive liquid that solidifies by a polymerizationreaction induced either thermally or by radiation. Extrusion coating, issimilar to hot-melt coating.

[0136] In extrusion coating, a film of molten polymer is depositedbetween two moving webs in a nip created by a rubber pressure roll and achrome-plated steel chill roll. In this continuous operation, rolls ofmaterial are unwound, new rolls are automatically spliced on the fly,and the surface of the substrate is prepared by chemical priming orother surface treatment to make it receptive to the extrusion coating,and to help develop adhesion between the two materials.

[0137] Coatings may be applied directly to the substrate, or may be castto another surface, dried, and later transferred to the substrate. Thistransfer coating process is used for manufacturing of, for example,pressure-sensitive label stock: the adhesive is first applied to asilicone-coated release liner, dried, and then laminated to the labelface stock. Coatings may be applied to the web material wound in rolls,or to precut sheets. Items such as disposable plates and trays may beformed by pressing coated paperboard blanks between forming dies, asdisclosed in Shanton, U.S. Pat. No. 5,776,619, incorporated herein byreference.

[0138] In one embodiment, films or sheets comprising a PHA are used tolaminate a substrate, such as paper. As used herein, “film” means anextremely thin continuous piece of a substance having a high length tothickness ratio and a high width to thickness ratio. While there is norequirement for a precise upper limit of thickness, a preferred upperlimit is about 0.254 mm, more preferably about 0.10 mm, and even morepreferably about 0.05 mm. As used herein, “sheet” means a very thincontinuous piece of a substance, having a high length to thickness ratioand a high width to thickness ratio, wherein the material is thickerthan about 0.254 mm. Sheeting shares many of the same characteristics asfilm in terms of properties and manufacture, with the exception thatsheeting is stiffer, and has a self-supporting nature.

[0139] Articles comprising PHAs, such as sheets and films, may be madeby any art-recognized process, such as those disclosed in Noda, U.S.Pat. Nos. 5,618,885 and 5,602,227, incorporated herein by reference. Forexample, films may be processed using conventional procedures forproducing single or multilayer films on conventional film-makingequipment. Sheets may be thermoformed. As used here, “thermoforming”refers to a process by which planks or sheets of the polyhydroxyalkanoteare heated until flexible and then stamped or vacuum pulled into theproper shape. Generally a sheet is fed through an oven and heated tobring it to a thermoformable temperature. The sheet is heated to asoftening point and then advanced to a forming station. Alternatively, asheet may move directly from an extruder to a forming station by meansof a series of rolls, which can either be heated or cooled to bring thesheet to the proper thermoforming temperature. The forming stationcomprises molds or stamps of the desired shapes.

[0140] Several preferred embodiments are illustrated in the followingnon-limiting examples.

EXAMPLE 1 Printed Paper Coated with a Laminated Layer ofpoly(3-hydroxybutyrate-co-3-hydroxyhexanoate) polymer

[0141] A film of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) 12.1%hexanoate (PHB-Hx 12.1%) is prepared from extrusion from the melt. Theneat PHB-Hx powder is run through a Haake single screw extruder fittedwith a strand die at 130° C. The strand is run through a water bath at atemperature of 60 C. The strand is run through Berlyn pelletizer tocreate pellets. The pellets are fed into a hopper of the Haake singlescrew extruder with a 6 inch flat die. The screw barrel and dietemperatures are set at 150 C. The film is taken up with Haake cast filmhaul off unit, with release paper separating the PHA film layers in theroll to prevent blocking. The film has a nominal thickness of 2 mil. Thefilm is cut into sheets that are approximately 10 inches long and 4inches wide. The film sheet is placed on top of common copier paper(Georgia Pacific Spectrum DP white), so placed to cover one half of thepaper sheet surface. The sheet assembly is placed between release paper(Idesco) and fed into an 8″ laminator (Idesco model 7000) operating at85 C. The sheet is allowed to cool. The resulting coated paper is thenfed into a Xerox 5750 laser printer by placing it the normal paper tray.A test image is printed on the paper. The resulting image is clear andthe toner is fused securely to the coated side. The coated surface isglossier than the uncoated surface, and the image appears sharper to theeye than the uncoated part of the paper.

EXAMPLE 2 Wrapping Paper Coated with a Laminated Layer ofpoly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/Plasticizer Blend

[0142] A film of a blend ofpoly(3-hydroxybutyrate-co-3-hydroxyhexanoate) 12.1% hexanoate, (PHB-Hx12.1%)/Triacetin/polyhydroxybutyrate (PHB) in proportion of 85/12/3 isprepared from extrusion from the melt. The neat PHB-Hx power, PHBpowder, and triacetin is run through a Haake twin screw extruder fittedwith a strand die at 150 C. The strand is run through a water bath at atemperature of 40 C. The strands run through a Berlyn pelletizer tocreate pellets. The pellets are fed into a hopper of a Haake singlescrew extruder with 6 inch flat die. The screw barrel and dietemperatures are set 130 C. The film is taken up with Haake cast filmhaul-off unit, with release paper separating the PHA film layers toprevent blocking. The film has a nominal thickness of 2-4 mil. The filmis cut into sheets that are approximately 10 inches long and 4 incheswide. The film sheet is placed on top of common copier paper (GeorgiaPacific Spectrum DP white), so placed to cover one half of the papersheet surface. The sheets assembly is placed between release paper(Idesco) and is fed into an eight inch laminator (Idesco model 7000)operating at 85 C. The sheet is allowed to cool. The paper is then fedinto a Xerox 5750 laser printer, placed in the normal paper tray. A testpattern is printed on the paper. The resulting image is clear and thetoner is fused securely to the coated side of the paper. The coatedsurface is glossier than the uncoated surface and the pattern appearssharper to the eye than the uncoated part of the paper.

EXAMPLE 3 Wrapping Paper Coated with apoly(hydroxybutrate-co-hydroxyhexanoate) polymer via a Liquid Suspension

[0143] An emulsion of PHA is prepared in the following manner. 5 g ofpoly(hydroxybutrate-co-hydroxyhexanoate) 11.1 mol % hexanoate (PHB-Hx11%) is dissolved in 45 g acetone at 50 C. until the solution iscompletely clear. The solution is precipitated by slow addition ofexcess methanol (ca. 5×) and forms a precipitate. The dry precipitate isthen ground with a Wiley mill grinder until a fine (ca. 30 mesh) powderis obtained. The powder is resuspended in 45 g of hexane. The suspensionis stirred with a magnetic stirrer.

[0144] A frame is placed on the paper to be coated (Georgia PacificSpectrum DP white). The frame is about 12 cm wide by 20 cm inches tallby 0.5 mm in height and serves to allow a particular amount ofsuspension to be placed on the paper. Approximately 120 ml of themixture is poured in the frame and excess emulsion is removed by runninga steel bar over the top of the frame. The sheet is allowed to dry in ahood. The paper is then placed in a Carver press between sheets ofrelease paper and pressed at 80 C. at 5000 lb. for 60 seconds. The paperis removed and allowed to cool. The paper is then fed into a Xerox 5750laser printer. A test pattern is printed on the paper. The resultingpattern is sharp and clear. the toner is fused securely to the coatedside. The coated surface is glossy and the image appears sharper to theeye than the uncoated part of the paper.

EXAMPLE 4 Melt-Coated Paper withPoly(3-hydroxybutyrate-co-3-hydroxyoctanoate) (PHB—O)

[0145] Films of poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) (PHB—O)are made in the following manner. About 2.5 grams ofPoly(3-hydroxybutyrate-co-3-hydroxyoctanoate) (8.4%) octanoate contentare placed between two 0.25 mm thick Teflon sheets into a brass shim ofthickness 4 mil. The Teflon, shim and polymer are placed between steelplates and heat pressed in a Carver press (Menomonee Falls, Wis.) at 145C. at 5000 lb. force for not longer than 3 minutes. The polymer andTeflon sheets are then removed and placed between 2 kg steel plates forat least 20 minutes to quickly crystallize film at the ambienttemperature (25° C.). In this way, 12 cm square films of PHB—O ofthickness 4 mil can be made. Coated papers are made by placing the filmsheet on top of common copier paper (Georgia Pacific Spectrum DP white).The film and paper is placed between release paper (Idesco) and fed intoan 8″ laminator (Idesco model 7000) operating at 85 C. The sheet isallowed to cool. The resulting coated paper is then fed into a Xerox5750 laser printer by placing it the normal paper tray. A test image isprinted on the paper. The resulting image is clear and the toner isfused securely to the coated area.

EXAMPLE 5 Coating of Poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) onPaper

[0146] In order to make a coating, 0.3 g ofPoly(3-hydroxybutyrate-co-3-hydroxyoctanoate) 8.4% octanoate (PHB—O 8.4)is dissolved in 9 ml of CHCl₃ at 50 C. until the solution is clear. ATeflon sheet placed over a 5 kg aluminum plate. The sample of paper tobe coated is placed over Teflon sheet and a 8 cm diameter glass cylinderis placed on the paper. The paper in this case is Georgia PacificSpectrum DP white. The solution is then poured into the glass cylinderand allowed to evaporate slowly at room temperature for 12 hours. Aftertwelve hours the glass cylinder is removed, the paper coating issmoothed by pressing in a Carver Press for 140° C. at 2000 lb. for 30sec.

[0147] The coating is impervious to water and can be printed on with alaser printer such as a Hewlett Packard laser jet 5C.

EXAMPLE 6 Coating of Paper from a Slurry ofpoly(hydroxybutrate-co-hydroxyhexanoate)

[0148] A slurry of poly(hydroxybutrate-co-hydroxyhexanoate) (PHB-Hx) wasprepared by adding approximately 20 g PHB-Hx (11.1% in powder form with100 g of ice in a Waring blender. The mixture was stirred for 20 minutesin a Waring blender at its maximum rpm. The resultant pulverized powderof PHA is mixed into water in at about 25% weight PHA, and the slurry isdeposited on a sheet of paper (George pacific DP white). A small frameof 1 inch wide by 4 inches long by ¼ inch deep is placed on the paperand the slurry is poured into the frame. After the slurry is dried, the:powder PHA coating on the paper is fixed by placing the sheet of paperbetween release paper sheets and inserting the assembly into a laminator(Idesco) operating at 85° C. The coated segment of paper can be printedon by placing the sheets in a Xerox 5750 laser printer and printing atest pattern on the coated part. The toner is fused securely to thecoating. The coating also resists penetration to grease and water. If asmall amount (10 ml) of water or canola oil is placed on the coated sideof the paper, the paper does not discolor from the water or oil.

EXAMPLE 7 Printed Paper Coated with a Laminated Layer of poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) PHB—O polymer

[0149] A film of poly(3-hydroxy butyrate-co-3-hydroxyoctanoate) 13%octanoate, (PHB—O 13%) is prepared from extrusion from the melt. Theneat PHB—O powder is run through a Haake single screw extruder fittedwith a strand die at 130° C. The strand is run through a water bath at atemperature of 60° C. The strand is run through Berlyn pelletizer tocreate pellets. The pellets are fed into a hopper of the Haake singlescrew extruder with a 6 inch flat die. The screw barrel and dietemperatures are set at 145° C. The film is taken up with Haake castfilm haul off unit, with release paper separating the PHA film layers inthe roll to prevent blocking. The film has a nominal thickness of 1-2mil. The film is cut into sheets that are approximately 10 inches longand 4 inches wide. The film sheet is placed on top of common copierpaper (Georgia Pacific Spectrum DP white), so placed to cover one halfof the paper sheet surface. The sheets assembly is placed betweenrelease paper (Idesco) and fed into an 8″ laminator (Idesco model 7000)operating at 85° C. The sheet is allowed to cool. The resulting coatedpaper is then fed into a Xerox 5750 laser printer by placing it thenormal paper tray. A test image is printed on the paper. The resultingimage is clear and the toner is fused securely to the coated side. Thesurface is glossier than the uncoated side and the image appears sharperto the eye than the uncoated part of the paper.

EXAMPLE 8 Printed Paper Coated with a Laminated Layer of poly(3-hydroxybutyrate-co-3-hydroxyoctanoate polymer Produced from Solution Cast Film

[0150] A film of poly(3-hydroxy butyrate-co-3-hydroxyoctanoate (13%octanoate), PHB—O 13% is prepared from casting from acetone.Approximately 5 g of the neat PHB—O powder is dissolved in 200 ml ofacetone at 50° C. The solution is stirred for at least three hours untilthe solution is clear. The solution is then poured into circular shallowTeflon dish approximately 5 inches in diameter. The dish is placed in aoven, an the solvent is allowed to evaporate slowly overnight (10-12hours) to produce a transparent film. The film has a nominal thicknessof 1-2 mil. The film sheet is placed on top of common copier paper(Georgia Pacific Spectrum DP white), so placed to cover one half of thepaper sheet surface. The sheets assembly is placed between release paper(Idesco) and fed into an 8″ laminator (Idesco model 7000) operating at85° C. The sheet is allowed to cool. The resulting coated paper is thenfed into a Xerox 5750 laser printer by placing it the normal paper tray.A test image is printed on the paper. The resulting image is clear andthe toner is fused securely to the coated side. The surface is glossierthan the uncoated side and the image appears sharper to the eye than theuncoated part of the paper.

EXAMPLE 9 Fabric Laminated with a Layer of poly(3-hydroxybutyrate-co-3-hydroxyoctanoate polymer Produced from Solution Cast Film

[0151] A film of 13% octanoate, (PHB—O 13%) is prepared from castingfrom acetone. Approximately 5 g of the neat PHB—O powder is dissolved in200 ml of acetone at 50° C. The solution is stirred for at least threehours until the solution is clear. The solution is then poured intocircular shallow Teflon dish approximately 5 inches in diameter. Thedish is placed in a oven, an the solvent is allowed to evaporate slowlyovernight (10-12 hours) to produce a transparent film. The film has anominal thickness of 1-2 mil. The film sheet is placed on top of a 5inch square section of untreated cotton fabric. The assembly is placedbetween release paper (Idesco) and placed into a Carver Press preheatedto 100 C. The fabric/PHA assembly is pressed for 20 seconds at 1000 lbs.The resulting coated fabric is then removed from the press and allowedto cool. The fabric is then subjected to the following test to check forgrease resistance and water resistance. About 20 ml of canola oil isplaced on the PHA coated side of the fabric and allowed to remain for 1hour. The fabric is free of oil stains that would indicate penetrationof the oil. About 20 ml of tap water is placed on the PHA coated side ofthe fabric and allowed to remain for 1 hour. The fabric is free ofdarkening that would indicate penetration of the water.

EXAMPLE 10 Fabric Laminated with a Layer ofpoly(3-hydroxybutyrate-co-3-hydroxyhexanoate) polymer Produced from MeltPressed Film

[0152] A film of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) 11.1%hexanoate (PHB-Hx-11.1%) is prepared by placing 5 g of powder of thePHB-Hx between two Teflon sheets then inserting this in a Carver presspreheated to 140 C. The PHB-Hx is pressed at approximately 7,000 lb.force for 2 minutes. The PHB-Hx is removed from the press and allowed tocool. The PHB-Hx is now in the form of a film sheet of about 3 milthickness. The film sheet is placed on top of a 5 inch square section ofuntreated cotton fabric. The assembly is placed between release paper(Idesco) and placed into a Carver Press preheated to 100° C. Thefabric/PHA assembly is pressed for 20 seconds at 1000 lbs. The resultingcoated fabric is then removed from the press and allowed to cool. Thefabric is then subjected to the following test to check for greaseresistance and water resistance. About 20 ml of canola oil is placed onthe PHA coated side of the fabric and allowed to remain for 1 hour. Thefabric is free of oil stains that would indicate penetration of the oil.About 20 ml of tap water is placed on the PHA coated side of the fabricand allowed to remain for 1 hour. The fabric is free of darkening thatwould indicate penetration of the water.

[0153] Additional embodiments and modifications within the scope of theclaimed invention will be apparent to one of ordinary skill in the art.Accordingly, the scope of the present invention shall be considered inthe terms of the following claims, and is understood not to be limitedto the details or the methods described in the specification.

What is claimed is:
 1. A coated substrate comprising a substrate and acoating comprising a biodegradable polyhydroxyalkanoate copolymer,wherein the biodegradable polyhydroxyalkanoate copolymer comprises afirst randomly repeating monomer unit having the structure:

wherein R¹ is H or a C₁₋₂ alkyl, and n is 1 or 2; and a second randomlyrepeating monomer unit having the structure:

wherein R² is a C₃₋₁₉ alkyl or a C₃₋₁₉ alkenyl; and wherein at least 50%of the randomly repeating monomer units have the structure of the firstrandomly repeating monomer unit, and wherein the substrate is selectedfrom the group consisting of paper, fabric, thread and yarn.
 2. A coatedsubstrate according to claim 1, wherein the biodegradablepolyhydroxyalkanoate copolymer further comprises a third randomlyrepeating monomer unit having the structure:

wherein R³ is H, a C₁₋₁₉ alkyl or a C₁₋₁₉ alkenyl, and m is 1 or 2; andwherein the third randomly repeating monomer unit is not the same as thefirst randomly repeating monomer unit or the second randomly repeatingmonomer unit.
 3. A coated substrate according to claim 1, wherein R¹ isa C₁₋₂ alkyl and n is
 1. 4. A coated substrate according to claim 1,wherein R¹ is H and n is
 2. 5. A coated substrate according to claim 1,wherein the coating is substantially free of plasticizers.
 6. A methodof improving the resistance to grease of a subtrate, comprising the stepof applying a coating to a substrate selected from the group consistingof paper, fabric, thread and yarn, wherein the coating comprises abiodegradable polyhydroxyalkanoate copolymer comprising two randomlyrepeating monomer units wherein the first randomly repeating monomerunit has the structure:

wherein R¹ is H or a C₁₋₂ alkyl, and n is 1 or 2; and the secondrandomly repeating monomer unit has the structure:

wherein R² is a C₃₋₁₉ alkyl or a C₃₋₁₉ alkenyl; and wherein at least 50%of the randomly repeating monomer units have the structure of the firstrandomly repeating monomer unit.
 7. A method according to claim 6,wherein the biodegradable polyhydroxyalkanoate copolymer furthercomprises a third randomly repeating monomer unit having the structure:

wherein R³ is H, a C₁₋₁₉ alkyl or a C₁₋₁₉ alkenyl, and m is 1 or 2; andwherein the third randomly repeating monomer unit is not the same as thefirst randomly repeating monomer unit or the second randomly repeatingmonomer unit.
 8. A method according to claim 6, wherein R¹ is a C₁₋₂alkyl and n is
 1. 9. A method according to claim 8, wherein R¹ is a C₁alkyl.
 10. A method according to claim 6, wherein R¹ is H and n is 2.11. A method of coating a substrate, comprising the step of applying acoating to the substrate, wherein the coating comprises a biodegradablepolyhydroxyalkanoate copolymer comprising two randomly repeating monomerunits wherein the first randomly repeating monomer unit has thestructure:

wherein R¹ is H or a C₁₋₂ alkyl, and n is 1 or 2; and the secondrandomly repeating monomer unit has the structure:

wherein R² is a C₃₋₁₉ alkyl or a C₃₋₁₉ alkenyl; and wherein at least 50%of the randomly repeating monomer units have the structure of the firstrandomly repeating monomer unit, and wherein the substrate is selectedfrom the group consisting of paper and fabric.
 12. A method according toclaim 11, wherein the step of applying the coating to the substratecomprises laminating the substrate with a film comprising thebiodegradable polyhydroxyalkanoate copolymer.
 13. A method according toclaim 12, wherein the film is a solution cast film.
 14. A methodaccording to claim 12, wherein the film is a melt pressed film.
 15. Amethod according to claim 11, wherein the step of applying the coatingto the substrate comprises: (a) preparing a coating compositioncomprising polyhydroxyalkanoate copolymer; (b) applying the coatingcomposition to the substrate to obtain a coated substrate; and (c)allowing the coated substrate to dry.
 16. A method according to claim15, further comprising the step subjecting the substrate to pressure.17. A method according to claim 15, wherein the coating composition is asolution.
 18. A method according to claim 15, wherein the coatingcomposition is a slurry.
 19. A method according to claim 15, wherein thecoating composition is a suspension.
 20. A method according to claim 11,wherein the step of applying the coating to the substrate comprisesextrusion coating the substrate.